This invention relates to a device, assembly, and method for holding a piece, such as a fastener, in a bore. The invention will be described in its application to fastener retainers, but it will become apparent that the invention has broader utility.
The use of fastener retainers to pre-attach bolts, studs, or other fasteners to a workpiece, such as a panel, in preparation for a subsequent assembly operation is well known. In a typical general application, a bolt (or other fastener) is inserted into a plastic annular retainer which is designed to retain the bolt within a smooth-walled bore of a workpiece. The retainer, which has an outer diameter slightly larger than that of the bore, is pressed into the bore, where it is held by resilient frictional engagement with the bore wall, thus pre-attaching the bolt to the workpiece. The workpiece may subsequently be associated with a second workpiece having a threaded bore which is axially aligned with the bore of the first workpiece, and the two workpieces may then be securely assembled to each other by engaging the bolt with the threaded bore of the second workpiece. See, for example, U.S. Pat. Nos. RE 36,164 and 6,039,525.
In a typical specific application, to minimize manual labor on an engine assembly line where oil pans are attached by bolts to engine blocks, fastener retainers can be used to pre-attach bolts to the oil pan, and the assembly of the oil pan and the bolts in their retainers can be moved to an assembly line for attachment to an engine block. Such pre-attachment improves production efficiency by eliminating the need for manual placement of the fasteners as parts of the engine assembly operation.
In using fastener retainers, it is often important that the holding power of the retainer to the fastener and the holding power of the retainer to the workpiece bore be such that the retained fastener may, if inadvertently bumped, slide axially of the retainer without the retainer slipping out of the workpiece bore. It is also desirable to provide a retainer that accommodates misalignment of bores and that permits the fastener to be tilted relative to the axis of the retainer. Furthermore, it is desirable that the design of the retainer readily accommodate varying requirements for retainer holding power and varying fastener and bore diameters, and that the retainer be capable of being manufactured simply and economically.